[Surgical technical note: apropos of cerebrospinal fluid fistula of the skull base].

Signs of a fistula of the C.S.F. may be deceiving and difficult to relate to the cause: posterior secretions of the cavum, whooping cough, headache on swallowing, fever, and asthenia, meningitis. The seat of the fistula is sometimes difficult to determine, necessitating multiple investigations with a high performance scanner, magnetic resonance imaging, scintigraphy. The increased pressure of the C.S.F. caused by general anaesthesia may be an aid in the radiological discovery of the fistula. Sealing is preferably performed by the low approach with the help of a lumbar drain for a few days in the case of major C.S.F. leakage. The graft material used to seal the fistula is either dermo-fatty tissue, or, if the fistula is narrow, an osseous wedge forming a kind of stopper.